Means for supervising pneumatic fire alarm systems



Jan. 1, 1935. E. A. LOWE Er AL MEANS FOR SUPERVISING PNEUMATIC FIRE ALARM SYSTEMS Filed Dec. 27, 1929 Patented Jan. 1, 1935 UNITED STATES MEANS FOR SUPERVISING PNEUMATIC FEE ALARM SYSTEMS Ernest A. Lowe and .toim a. Hamilton, Cleveland Heights, Ohio, assignors to Automatic Sprinkler Company of America, Cleveland, Ohio, a

ration of Delaware Application December 2'71, 1929, Serial No. M16382 8 @laims.

This invention relates to fire alarm signal apparatus in which a line of air tubing is employed extending over or disposed through the area to be protected and operating. in response to abnormal rate of change of temperature, the

will, by electrical or other means, cause an alarm or signal to be given.

Attempts have been made to supervise electrically air or gas tubing or pneumatic thermostats by different methods such as small insulated copper wire drawn through the tube or air chamber, insulated therefrom and having the customary trouble relay bell and battery to indicate shorts, breaks or grounds or by electrically insulating the tube or air thermostat, using it as one leg of a supervised electric circuit with the customary balanced relays in said circuits to register any disturbance of same but such electrical means have not been entirely successful in operation.

.One of the objects of the present invention is to provide a prompt, reliable and effective pneumatically operated means for detecting breaks or abnormal leakages in said air or gas tubing which would impair the operation of the same was the means for detecting fire, and the specialobject of the invention is to provide means for promptly detecting such a break at whatever point it may occur in the length of tubing.

Generally stated the invention consists in the improved constructions hereinafter described and claimed wherein the tubing at both of its ends is provided with a pressure responsive device controlling the action of an alarm or signal and operating on sudden change of air pressure consequent upon a break or large leakage in said tubing, the normal pressure on saiddiaphragm being normally balanced by means opposing the pressure in the tubing so that on the occurrence of such breakage and the consequent change of pressure the diaphragm becomes unbalanced and will be moved to cause an alarm to be given, all as more particularly hereinafter described and claimed.

In the preferred manner of carrying out the invention we employ as the means for closing an electric circuit or otherwise producing an alarm indicating a break of the tubing the same diaphragm or similar device which is employed for giving an alarm or signal of fire on a sudden increase of the air pressure in said tubing due to abnormal rate of rise of temperature at any point in the area to be protected.

The invention relates also to the means for (Cl. ll77355) maintaining the air pressure. The object of this part of the invention is to prevent the giving of a'false signal of fire through a temporary interruption in the normal action of the. air

supply devices.

In carrying out the latter object we employ a source of supply of air or other gas under pressure preferably in the form of an automatically controlled pump and in connection with said diaphragm or its casing we employ an exterior casing in which the pump or other means normally maintains a pressure. Said casing is connected with the diaphragm casing only through a restricted vent or passageway which throttles down the escape of air from the diaphragm casing should there be a temporary failure of the pump or pressure supply .in the outer casing, and thereby prevents any sudden movement of the diaphragm in the detector diaphragm casing such as would normally result from a sudden k change in the relative pressures upon the opposite faces thereof due to sudden change in the pressure on the side thereof which connects with the detector tubing.

By providing the two diaphragms or similar device either of which will respond and give a signal on the sudden decrease of pressure due to rupture of the tubing we insure the prompt giving of a signal of breakage no matter where, in the length of tubing, the break may occur, since if it should occur near the center both diaphragms would respond and the retardation due to slow escape through the small gauge tube would be only that due to one-half of the length of said tube while if occurring at one side of the center or near either end the break would be indicated more promptly by the movement of the diaphragm near that end and would thereby compensate for any delay in the action of the diaphragm at the extreme other end of the tubing. Furthermore in case the diaphragm nearest the break should fail to cause a signal the diaphragm at the opposite end would act though somewhat later.

In the accompanying drawing:

Fig. 1 illustrates our invention in one of its forms in diagrammatic fashion, the portion of the apparatus comprising the diaphragms and diaphragm casings being illustrated in vertical section.

Fig. 2 is an enlarged vertical sectional view of the diaphragms, their casings, electrical contacts and detector tubing connections. I

The usual or typical system of air or gas tubing is indicated at 7. customarily this is 1000 feet in length more or less and may cover the fire area with the portions of tubing no closer to one another than 30 feet between centers. The opposite ends of said tubing terminate in the enclosing casings 6 for a pair of diaphragms indicated at 6 upon which gas pressure from the tubing 7 acts to cause the diaphragm to move and close circuit upon normally open circuit contacts for the purpose of sending a fire signal, but only when the rate of change of pressure in the tubing exceeds the rate of compensation for pressure permitted by or restricted by a vent or relief 9 at each end of the tubing which vents into a chamber or receptacle in which air pressure is maintained and from which the tubing derives its air pressure as will be presently described.

It is obviousthat under the general conditions so far described any serious break or leak in '7 might interfere with the operation just at the time when it is required to operate in response to fire conditions, and one of the features of our invention consists in the provision of suitable means whereby, through the production of an unbalanced action of either or both of two diaphragms arranged at opposite ends respectively of the tube 7, resulting from such break or leak a signal or indication will be promptly given no matter at what point such break or leak may occur.

As indicated more fully in the enlarged view Fig. 2the diaphragms 6 are suitably mounted in a diaphragm casing or casings 6 shown in crosssection, which may be of bakelite or other suitable material. These diaphragm containing casings may be mounted or attached together and suitably secured, as shown in Fig. l and are both enclosed within a common casing or receptacle 5 which is gas tight excepting for the gas connections and vent to be presently described. In association with each diaphragm two contacts A, B, are employed. These are mounted in position opposite the electrical contact carried by the center of the diaphragm, the mounting of them being in the diaphragm casing as shown. Contacts A may be in multiple in the same circuit and contacts B may be likewise connected in multiple in their circuit. Back of each diaphragm or, in other words, on the side thereof opposite that exposed to the pressure from the tubing, there is a gas space in free communication, by openings 5, with the case or receptacle 5. In casing 5 is a restricted equalizing air or gas vent or passageway indicated at 8 through which gas pressure in 5 and in another outer gas tight casing or enclosure 4 may be gradually equalized. The particular functions of this passageway permitting gradual transfer of pressure between the chambers will be described further on. Any pressure maintained in chamber 4 automatically by the means to be presently, described will be communicated, through vent or passageway 8, to the chamber or enclosure 5 and said pressure in 5 will act freely upon the sides of the diaphragms opposite the sides exposed to the pressure from the tubing 7 and will be communicated from 5 to the tubes through the vents or restrictions 9 to maintain the air pressure or condition therein esa-eve various conditions are employed and also suitable automatically controlled means consisting for instance of an air or gas compressor for maintaining a substantially continuous predetermined pressure in the outside casing or chamber 4.. The connection and action of these devices will be now described in connection with the operation of the diaphragms. Normally the diaphragms stand in the position shown since the normal pressure from tubing 7 acting on one side of the diaphragm is balanced by an opposing action of any suitable means acting on the opposite side of the diaphragm and consisting, by preference as shown, of air or gas pressure.

In the usual and normal operation for signalling the existence of fire, increased pressure will be produced in the tubing 7 and the diaphragms, one or both, will be moved to make contact with the B set of contacts. A serious or abnormal break or leakage in tubing '7 will, on the other hand, cause decrease of pressure in the diaphragm casings and permit the diaphragms, one or both, to move under the unbalanced action behind them normally opposing the pressure in the side connected to the tubing wherf one or both will make contact with contacts A due to the superior pressure then existing in case 5. The registering of such break or abnormal leak may be effected by any desired means, as for instance through circuit shown by wires 11 and 10 connected respectively to the pair of contacts A and the diaphragms, said circuit including battery 25 and releasing magnet 41 which will operate to actuate or release the usual trouble clock or transmitter indicated at 22, the latter in turn operating through circuit 22', battery 24, and register 23, to produce a trouble signal at the central station or other suitable supervisory point thus giving a warning of a derangement of the tubing.

If the break or excessive leak in the tubing should occur near an end thereof remote from either diaphragm 6' so that said diaphragm would not, owing tov the length and friction of the tubing, respond quickly to a decreasing pressure produced by said break thereby causing dangerous delay in the action of the trouble signal 23, such delay would be rectified or compensated for by the prompt action of the dia phragm at the opposite end of the tubing or near the break since in this instance the decrease of pressure in the space connected to said near end could take place rapidly and to such degree of rapidity that the vent or restricted inlet 9 would be ineffective to compensate for the decrease in pressure thereby produced. Hence the diaphragm 6', at said end near the break would move up quickly and give the trouble signal although the action of the diaphragm at the opposite or remote end should be dangerously delayed. This trouble signal or alarm will be given promptly therefore no matter where the break in the tubing occurs. At the same time the diaphragms 6' are capable of functioning in the usual or intended way to promptly give a fire signal in case of the sudden change of pressurein the tubing wherever it may occur, by the closure of circuit on one or both contacts B over circuit 10-'-10' and battery 25. This circuit includes the main or release magnet 17 ,for fire clock or transmitter 18 that transmits the code signal or alarm over wires 18', battery 19 and fire register 20 located in the central station by the action of magnet 17. Simultaneber in which the reservoir or pressure is mainously a local alarm will be given by the action of magnet 17 which closes the circuit over con tact 21', annunciator relay 21, bell 40 and battery 25.

The circuiting of these systems may be super= vised by the usual trouble relay 1%, bell l6, battery 15 and circuits 16', having the usual re sistance 12 and ammeter13 to keep a uniform supervisory flow over the main circuits.

Supervisory air or gas pressures different from atmospheric pressure of approximately uniform degree maybe automatically maintained in cases 4 and 5 and the tubing 7 by compressor 3 shown as electrically driven feeding through valve 26 and automatic back pressure check 75 into case 4, having pressure electric control switch 28 that through circuits 30, 30' and 31 and electric supply 29 automatically starts the corn= pressor when contact on pressure gauge 28 low= ers' to the predetermined low point and auto: matically cuts off and stops the compressor when the compressor establishes the desired high point, this being accomplished by the usual lost motion yoke 42 on the contact point, adjustable for the range at which compressor will start and stop.

It is obviousthat the pressure may be either minus or plus according to the temperature conditions under which the apparatus is used as cold storage might require minus pressure to be safe against freezing; warm buildings could sate ly be handledwith plus pressures, Should the compressor 3 fail to start when pressure switch 28 reaches the low starting point or if by virtue of destruction or excessive leakage of box a the leak should exceed the limit or" compressor 3, pressure switch arm of gauge 27 will continue to drop until contact is made through circuits 3i and 32 and magnet 32 and electric supply 29, thus energizing trouble magnet 32, thereby starting trouble clock 33 and sending code signal over wires 34-, battery 34, and trouble register 35, usually located in central station. in addition, by bell 37, annunciator relay 3d and contact 43, a local alarm may be indicated simultaneously through the action or the magnet 32 in closing circuit on contact 48. 3t and 39 indicate the usual cut-off valves in the connections to the pressure of a gas.

It will be understood that the supervisory or artificial pressure produced by the above or any other suitable means in the exterior chamber and from which the tubing 7 derives its pressure through the restricted passageway serves the purpose of establishing a difference of pressure on a diaphragm connected to the tubing so in case of rupture of said tubing the pressure in the tubing in becoming equalized with that 01 the air through the break produces a change of pressure on the diaphragm which is employed through suitable instrumentalities to produce a trouble signal. The air or gas said tub g normally maintained therein for the putpose also serves as the means for communicat ing pressure to the devices by which a fire alarm signal is produced when the air is heated expanded by increase of temperature due to enistence or" iire By using the exterior casing which or gas pressure is automatically maintained by the automatic pump or other means and connecting the same indirectly by the restricted vent or passage it with the casing 5 in which the dia= phragm chambers are placed we avoid false action oi the system due to a failure or break oi the air compressor system or detect in chann tained. It is obvious that were the air pressure supplied directly from the compressor to casing 5, failure of the air compressor or break or leakage in casing 5 would cause a fire signal to work, since in that case the sudden relief of pressure back of the diaphragms would cause the same to move over under the maintained pressure in the tubing 7. By means-however, of the restricted vent 8 connecting with the reservoir of pressure 4.- sudden drop of pressure in the chamber 5 and the diaphragm chambers is prevented in case of temporary failure of the compressor or excessive leak in casing 4 thereby avoiding the production of false signal of fire by the movement of the diaphragm which would thereby result so as to cause the same to move against the fire alarm contacts B. The restricted vent or opening 8 has a further beneficial effect in preventing sudden abnormal increase of pressure in casing from producing sudden changes of pressure in 5 and thereby avoids the production of false trouble signals by movement of the diaphragms in a direction to close the contacts A through which the trouble signal is given. Practically the tubing system is thereby made independent of breaks in the air compressor sys= tern which is, as above stated, provided with a notifying alarm in case said break should occur or compressor fail to restore the pressure, it being understood that when such alarm is given prompt action will be taken to rectify the trouble.

What we claim as our invention is:

l. in an apparatus or" the character described, the combination oi air or gas tubing and a diaphragm chamber connected to said tubing and having a contact operating diaphragm responsive to a change or" pressure in said tubing acting on one side of said diaphragm, cooperating contacts brought into action by said diaphragm on movement thereof in either direction, a casing or receptacle within which said diaphragm chamber is completely enclosed and in which constant pressure different from atmospheric pressure is automatically maintained and which is in free continuous connection with the opposite side of said diaphragm, means for automatically supplying substantially constant pressure to said receptacle and a restricted vent or opening from the tubing located within the receptacle and through which the tubing may derive a supply of air from said eceptacle.

2. in an apparatus of the character described, the combination of air or gas tubing, a diaphragm chamber having a contact operating exposed on one side to change of pressure in said tubing, a casing or receptacle for said diaphragm chamber having means for continuously maintaining pressure therein different from atmospheric pressure and in constant communication with the opposite side of said diaphragm, a restricted passage through which said continuously maintained pressure is communicated to said tubing, cooperating contacts brought into action by said diaphragm on movement thereof in either direction and an exterior casing surrounding said diaphragm chamher and connected to gas compressing means and having a continuously open restricted vent or passageway independent of the tubing and through which the gas pressure of said exterior casing is supplied to the casing for the diaphragnr 3. in an apparatus of the character described,

the combination oi or gas tubing provided with a pressure compensating vent, a diaphragm chamber in communication with said compensating vent and having a contact operating diaphragm having a chamber in connection with and responsive to change of pressure in said tubing cooperating contacts brought into action by said diaphragm on movement thereof in either direction and an outer chamber or casing within which said diaphragm casing is mounted, said outer casing or chamber being connected to gas compressing means provided with controlling devices responsive to change of pressure in said chamber and a continuously open restricted vent or passageway independent of said pressure compensating vent and affording a passage through which gas is supplied for action on the diaphragm in opposition to the tube pressure, said compressing means operating under automatic control to supply and maintain approximately constant pressure in said outer casing different from atmospheric pressure.

4. In an apparatus of the character described, the combination with detector air or gas tubing of a pair of diaphragms having means for subjecting them respectively to pressure communicated from opposite ends of said tubing adjacent to each other, a pair of contacts for each diaphragm located at opposite sides thereof and adapted independently to complete an electric circuit and respectively upon increase or decrease cf pressure in the tubing, a sealed chamber surrounding and within which .said diaphragms are both mounted and having free communication with the spaces on the sides of said diaphragm opposite the sides exposed to the tubing pressure, a restricted passage between the interior of the tubing and the sealed chamber, means for automatically maintaining substantially constant gas pressure in said chamber diiferentfrom atmospheric pressure comprising a receptacle in which such pressureis automatically maintained and which is connected with said chamber through a restricted passageway.

5. In an apparatus of the character described, the combination with detector gas tubing of a pair of diaphragms having means for subjecting them respectively to pressure communicated from opposite ends of said tubing adjacent to each other, a pair of contacts for each diaphragm located at opposite sides thereof and adapted independently to complete an electric circuit respectively upon increase or decrease of pressure in the tubing, a surrounding enclosure common to and within which said diaphragms are both mounted, said enclosure automatically maintaining substantially constant pressure in said enclosure different from atmospheric pressure, an exterior chamber surrounding and connecting with the first by a restricted vent and provided with means for automatically maintaining gas at a substantially constant pressure in the exterior chamber different from atmospheric pressure.

6. In an apparatus of the character described, the combination with detector tubing provided with means for maintaining therein air or gas pressure different from that of the atmosphere and provided with pressure compensating vents Lea ers at both ends adapted to allow equalization of pressure between pressure in said tubing and an exterior pressure when the pressure in the tubing varies at apredetermined slow rate, with a pair of pressure responsive devices connected respectively to the opposite ends of said tubing and each subject to variation of pressure maintained in said tubing, means for creating and automatically maintaining an opposing pressure different from atmospheric pressure upon each responsive device opposing the tubing pressure and derived from a common source through a passage independent of the pressure compensating device, an alarm or signal controlled in its action by either of said devices through sudden decrease of pressure in said tubing consequent upon a break or excessive leakage therein and an alarm or signal brought into action by each of said pressure responsive devices on an increase of the pressure in said tubing not compensated for by the pressure compensating vent.

7. Inan apparatus of the character described, the combination of detector tubing carrying an automatically maintained pressure different from atmospheric pressure and having a pressure responsive device at each end thereof responsive to a change of pressure in the tubing consequent either upon change of temperature or upon breakage of said tubing, means common to said pressure responsive device for automatically maintaining and providing a pressure normally balancing the pressure in the tubing by opposing action normally opposing the pressure in the tubing and acting at both ends thereof upon both said devices and means for giving an alarm or signal through movement of either of said devices under such opposing action upon an abnormal change of pressure in the tubing resulting from a break or leak and means for giving an alarm or signal in response to movement of either of them under uncompensated increase of pressure in the tubing due to heat.

8. Means for detecting changes of pressure condition in an air tubing provided with means for producing therein an automatically maintained pressure different from that of the atmosphere comprising a pressure responsive diaphragm and chamber therefor connected to the tubing so as to be exposed to the pressure therein on one side and exposed on its other to continuous maintained pressure different from atmospheric pressure, means for supplying such pressure from a chamber completely surrounding the diaphragm chamber and to which pressure difiicrent from atmospheric pressure is supplied from a suitable source having means for automatically maintaining pressure diflerent from atmospheric pressure, a restricted passage connecting the tubing and the said surrounding chamber having the automatically maintained pressure and a pair of fixedly mounted circuit closing devices cooperating with said diaphragm and adapted to be engaged thereby respectively upon movement of the diaphragm in response to increase or decrease of pressure in the tubing.

A. LQW'E. JOHN inuuncron. 

